This research core will facilitate the use of gene transfer and transgenes of fish in the different projects necessitating these technologies. The core will be setup to facilitate advice on transgenic construction, it will provide vectors and reporter genes, it will produce transgenic fish and screen the fish for the transgene. It will also provide instruction on handling and analyzing transgenic fish. Eventually, as new transgenic lines are produced that have firefly luciferase reporter genes, it will provide instructions on assaying the treated embryos and larvae for firefly induction by toxicants. In this context. the specific aims of this core will be: 1) To provide advice, vectors, cloned regulatory elements and reporter genes for the construction of transgenic vectors. For those laboratories not familiar with working with DNA, it will instruct individuals on how to make the transgenic constructs and/or make them for the laboratory. 2) To produce transgenic fish via DNA microinjection or pseudotyped retroviral vector infection. To screen the progeny of the potential transgenic founders to identify transgenic expressing progeny for the development of transgenic lines. To instruct individual, if desired, on the examination, breeding, and transgenic screening of the transgenic lines. 3) To collect and freeze down sperm from the transgenic lines for long- term storage. 4) To setup breedings so that embryos can be provided for treatment studies and to aid in the luciferase analysis of the IRES transgenic fish.